Hemophilic factor VIII C1- and C2-domain missense mutations and their modeling to the 1.5-angstrom human C2-domain crystal structure

Abstract

Factor VIII C domains contain key binding sites for von Willebrand factor (vWF) and phospholipid membranes. Hemophilic patients were screened for factor VIII C-domain mutations to provide a well-characterized series. Mutated residues were localized to the high-resolution C2 structure and to a homology model of C1. Of 30 families found with mutations in the C domains, there were 14 missense changes, and 9 of these were novel. Of the missense mutations, 10 were associated with reduced vWF binding and 8 were at residues with surface-exposed side chains. Six of the 10 mutants had nearly equivalent factor VIII clotting activity and antigen level, suggesting that reduced vWF binding could cause hemophilia by reducing factor VIII stability in circulation. When the present series was combined with previously described mutations from an online international database, 11 C1 and C2 mutations in patients with mild or moderately severe hemophilia A were associated with antibody-inhibitor development in at least one affected individual. Of these substitutions, 6 occurred at surface-exposed residues. As further details of the C1 structure and its interface with C2 become available, and as binding studies are performed on the plasma of more patients with hemophilic C-domain mutations, prediction of surface binding sites should improve, allowing confirmation by site-specific mutagenesis of surface-exposed residues.

Analysis of protein missense alterations by combining sequence‐ and structure‐based methods

“…The C2 domain (or discoidin domain) of FVIII is known to interact with negatively charged membranes and with other proteins such as von Willebrand factor (VWF) (Liu et al, ; Pratt et al, ). We investigated the potential molecular effect of two substitutions, Met2238Val (moderate) and Ala2201Pro (mild), located on this domain of FVIII, both associated with hemophilia A (Liu et al, ; Pratt et al, ; Spiegel et al, ; Villoutreix & Miteva, ). Table shows the results of the in silico analysis (PDB ID: http://www.rcsb.org/pdb/search/structidSearch.do?structureId=2R7E, UniProt ID: http://www.uniprot.org/uniprot/P00451).…”

“…Missense mutations identified in blood coagulation proteins can lead to life‐threatening illnesses. For example, amino acid changes in distinct regions of factor VIII (FVIII) can cause bleeding disorders (Hemophilia A) (Liu et al, ; Pratt et al, ; Spiegel, Jacquemin, Saint‐Remy, Stoddard, & Pratt, ). Of particular interest for the present study, some of the coagulation proteins including FVIII function properly only when they are anchored in an appropriate membrane surface.…”

Genotype-dependent response to desmopressin in hemophilia A and proposal of a predictive response score

“…(Arg2178His), displayed a significantly shorter median FVIII half-life (ranging from 2.20 to 3.10h; MIN-MAX, 0.70-4.50h) than other variants. These variants reside within the VWF interactive site that overlaps the FVIII C1-C2 domains [18][19][20] . Conversely, the mutated p.…”